1. Field of the Invention
The present invention relates to the field of vascular access devices, and more particularly, to devices and methods for positioning and retaining long-term vascular access catheters.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Vascular access catheters provide venous access to the central circulatory system of a patient. Vascular access catheters placed for a short time period, typically less than two weeks, are called acute catheters. For those medical conditions requiring long term access to the circulatory system, chronic or permanent vascular access catheters are used. These catheters are designed to remain within the patient for indefinite periods, often more than a year. Permanent or chronic venous access catheters are usually placed through a subcutaneous tunnel and include central venous catheters, dialysis catheters, peritoneal catheters, and peripherally inserted central catheters, also known as PICC lines.
The long-term catheter is typically used for the delivery of intravenous fluids, medications such as chemotherapy drugs and antibiotics, and blood products. Venous access catheters may also be used as access mechanisms for blood sampling and the administration of contrast agents during diagnostic Computer Tomography (CT) procedures. Dialysis catheters are used to access the venous system during hemodialysis, a medical procedure used to cleanse the blood of patients whose kidneys do not function properly.
Vascular access catheters are placed within the central circulatory system such that the catheter tip is exposed to high rate blood flow, typically in the right atrium. This allows rapid delivery and dilution of drugs into the bloodstream, and thus, more effective treatment. In the case of dialysis catheters, high flow rates provide faster and more effective blood cleansing. Optimal location of the catheter tip in a large blood vessel is also necessary in order to decrease the rate of catheter occlusion.
Another clinical requirement of vascular access catheters is that the catheter be placed so as to eliminate any dislodgement or movement of the catheter during long-term use. Catheter movement may result in sub-optimal treatment due to catheter tip misalignment Movement may also result in catheter leakage, infection and blood loss. Dislodgement of a vascular access catheter may even result in death, due to extensive blood loss from the jugular or other large vein.
To fix and retain the position of a long-term catheter in a patient's body, the catheter is typically inserted by tunneling the catheter through a subcutaneous tissue track. This tunneling technique may decrease infection rates at the site of cutaneous insertion, which is the primary site of entry for microorganisms on a catheter. Studies have shown that compared to standard catheter placement, tunneling decreases bacteria colonization.
To create a subcutaneous tunnel, a first incision is made in the patient's skin approximately several inches away from where the catheter will enter the target vein. A second incision is made at the location where the catheter will enter the vein. A tunnel track is created through the fascial tissue between the two incisions. The distal end of the catheter is then inserted into the first incision and advanced through the tunnel track where it emerges from the skin at the second incision, or exit site. The distal portion of the catheter is then inserted into the target vein.
Dialysis catheters are typically tunneled through the chest wall tissue, entering the internal jugular vein at the neck area. They may also be placed in the subdlavian vein just below the collar bone. Peritoneal catheters are tunneled from the peritoneum to the exit site of the catheter, near the navel. As with standard dialysis catheters, the main consideration with peritoneal catheters is the potential for infection at the exit site or peritonitis.
PICC lines, smaller in diameter, are typically introduced through the basilic or cephalic vein into the central circulatory system. Although traditionally PICC lines have been inserted directly into the target vein, placing PICC lines through a subcutaneous tunnel is an emerging trend. For these lines, the tunnel is usually created in the lower or upper arm region, with the catheter entering the target vein near the shoulder. Central venous catheters are larger in diameter than PICC lines and are typically placed when no peripheral veins are available, when medications cannot be introduced into a peripheral vein without vessel damage, or when central venous pressure monitoring is required. Tunneling of a central venous catheter is similar to the technique used for dialysis catheters.
Tunneled catheters may include a circular in-growth cuff attached to the outer surface of the catheter shaft near a bifurcation hub. The in-growth cuff is made of a porous or fibrous material which promotes tissue in-growth by allowing the tunnel track tissue to grow into the in-growth cuff material. The in-growth cuff thus acts as an anchor to help secure the catheter in place and prevent movement of the catheter. The in-growth cuff also helps to provide protection against infections related to vascular access catheters by sealing the tunnel track. The in-growth cuff prevents undesired movement and inadvertent removal of the catheter and thereby prevents excessive blood loss or death. Because it takes approximately two weeks for tissue to become fully incorporated into the in-growth cuff, the physician typically fixes the catheter to the patient's skin immediately after insertion. The catheter may be securely fixed to the patient's skin by sutures stitched through suture wings on the hub. Alternatively, an adhesive bandage or other skin attachment mechanism may be used.
To optimize treatment results, the distal tip of the catheter must be precisely placed in a large blood vessel such as the right atrium, and the in-growth cuff must be positioned and fixed inside of the patient's body. Positioning the catheter within the right atrium provides the high blood flow rates required for efficient dialysis, or in the case of PICCs, rapid delivery and dilution of drugs into the bloodstream, and thus more effective treatment. Optimal location of the catheter tip in a large blood vessel is also necessary in order to decrease the rate of catheter occlusion. Optimal placement of the catheter tip will make the catheter tip less likely to contact or rest up against the inside of a blood vessel wall, thereby blocking catheter ports, or causing damage to the vessel wall from the catheter.
Optimal catheter cuff placement is critical for secure fixation of the catheter over long periods of time. It is generally accepted that the ideal cuff placement is at a depth of at least 2 cm to approximately 3.5 cm from the incision entry site. This position provides for optimal in-growth of the cuff and secure fixation. Proper catheter cuff placement also ensures a tight seal between the catheter and the tunnel track, thereby reducing risk of infection, and associated complications. Cuffs placed too close to the incision site will result in sub-optimal fixation and the increased risk of peri-catheter leakage and infection. If the physician is forced to place the cuff deeper into the tunnel track than desired in order to achieve optimal catheter tip placement, catheter removal or exchange becomes problematic as it is difficult to remove a cuff that is too deeply tunneled. Studies have also shown that deep tunneling may lead to increased risk of catheter infection.
Patient comfort is directly related to the position of the cuff because cuff position determines where the catheter will be sutured to the patient's body. Most venous access catheters include a suture wing component attached directly to the bifurcation hub. Suturing the catheter in a less than optimal location on the patient's body may not only lead to discomfort but may also increase the risk of catheter movement or dislodgement. For example, if a catheter is sutured to a female's chest, the natural movement of the breast may compromise catheter fixation.
If optimal cuff placement cannot be achieved, the physician may not be able to utilize the suture wings for securement to the patient's skin. Instead, the physician may be forced to suture the catheter to the skin surface at a location distant from the suture wings. To do this, the physician will wrap the suture directly around the catheter shaft at the desired location. Although this method may achieve temporary fixation of the catheter until cuff in-growth occurs, it may compromise the catheter's lumen due to compression by the suture line. Reduced lumen diameter will result in reduced flow rates through the catheter, which in turn, will compromise treatment.
In summary, the difficulty associated with placement of the catheter tip and the catheter cuff is that the catheter tip and the cuff are fixed relative to each other. Thus, optimum positioning of one is likely to result in less than optimal positioning of the other, resulting in problems associated with treatment efficiency, catheter fixation, infection risk, patient comfort and comprised flow rates, as described above. Thus, there exists a need in the art to be able to independently position the tip and cuff during a tunneled catheter placement to ensure optimal positioning of all elements of the catheter.
Several different types of catheters have been developed in an attempt to address the need for precise positioning and maintenance of the catheter tip and cuff during catheter placement. For example, manufacturers of some vascular access catheters offer catheters of varying lengths to accommodate different patient anatomy and placement preferences. The catheter length requirement for catheter tip placement at the junction of the superior vena cava and right atrium is typically estimated by measuring the distance of the path from the tunneled insertion site to the right atrium. The appropriate length catheter is then selected by the physician. Commercially available catheter lengths often only approximate the ideal length, requiring the physician to adjust placement of the catheter, which may result in sub-optimal positioning. In addition, even if the overall length of a catheter is available, the desired distance between the cuff and tip varies by patient anatomy. To address this problem, physicians may customize the catheter by trimming the distal end of the catheter prior to placement Distal trimming is disadvantageous for several reasons. Trimming requires additional physician time to accurately measure and trim the catheter. Trimming the catheter may increase the chance of error in achieving the proper length and overall placement of the catheter. Trimming the end of the catheter can result in unwanted sharp edges, and the modified distal tip may hinder catheter advancement through the tunnel and into the vascular system. Trimming can also weaken the integrity of the catheter, thus compromising treatment efficiency or increasing the risk of shaft breakage. Additionally, some vascular access catheters have distal tips that are tapered or otherwise uniquely shaped and accordingly cannot be trimmed at all.
Several different types of catheters have been proposed to address the need for accurate catheter placement by first placing the catheter within the central venous system and then trimming the proximal end of the catheter shaft. The distal tip of the catheter is first placed in the desired location and then the proximal portion of the shaft extending outside of the patient's body is trimmed, after which a bifurcation or other hub configuration is attached to the proximal shaft end by the physician. Trimming the catheter proximally exposes less of the catheter to potential damage and ensures precise positioning of both the proximal and distal ends of the catheter, but there are key disadvantages to this technique. Typically, the cuff is permanently pre-attached to the catheter shaft and therefore cannot be adjusted independently of the catheter tip. This technique is also disadvantageous in that it requires the physician to perform additional steps to attach the hub after initial catheter placement, thereby increasing procedure time. Mechanically attaching a hub to a catheter shaft also increases the potential for leakage at the hub connection and presents concerns about the long-term structural integrity of the attached components.
Another type of commercially available device facilitates precise positioning of both the distal and proximal ends of the catheter by use of an attachable suture wing connector that may be mounted separately onto the catheter shaft This design provides for adjustable positioning of the suture wing, but does not provide for independent customization of the cuff position. In addition, the suture wing is not permanently affixed to the catheter shaft and thus may be inadvertently moved or even removed, resulting in the problems associated with sub-optimal catheter fixation.
There has not been proposed a catheter assembly that addresses the need for optimally and permanently customizing the position of the catheter cuff and the catheter tip relative to one another in a patient body during catheter placement The present invention addresses this need by utilizing a catheter retention assembly comprised of a cuff positioning device with an in-growth cuff and a securing means. The device includes a carrier system which, when mounted on a vascular access catheter, is slidably and longitudinally moveable along the catheter shaft. Once the catheter retention assembly is positioned as desired relative to the distal tip of the catheter, the cuff positioning device may be permanently fixed to the catheter shaft, thus providing a means for customizing the cuff position relative to the tip position. Once the cuff positioning device is locked in place on the catheter shaft, the catheter will not move or slip in relation to the cuff positioning device. Since a securing means is also mounted on the cuff positioning device, the physician is able to temporarily fix the exposed catheter in the desired location on the patient's skin until in-growth of the cuff has been established.
The combined design features of the current invention are not presently available in conventional catheters with fixed-position sutures and cuff assemblies. Using the device of the current invention to independently optimize cuff and tip placement eliminates problems with prior art devices and methods, including the problems of sub-optimal treatment outcomes, increased infection risk, compromised catheter integrity, insecure fixation and patient discomfort The instant invention may be applied to all types of vascular access catheters, including, but not limited to, hemodialysis catheters, peritoneal catheters, PICC lines, central venous catheters, and tunneled catheters, as described.
Accordingly, it is a purpose of the present invention to provide a catheter retention assembly, which provides for optimal, simultaneous, and permanent positioning of the catheter tip and the catheter cuff relative to one another during catheter placement by positioning the catheter tip and fixing the position of the cuff positioning device around the catheter. This enhanced permanent optimal placement will improve treatment outcomes and help lower the risk of infection in a patient, thereby enhancing the catheter's antimicrobial properties and ensuring that the lumen of the catheter is not compromised.
A further purpose of this invention is to provide a catheter retention assembly that will help to ensure that adjustment of the cuff automatically positions the external fixation mechanism such as a suture wing in the desired place on the patient's skin away from sensitive areas to ensure patient comfort, while not compromising the integrity of the catheter.
A further purpose of this invention is to provide a catheter retention assembly and method of placement that minimizes procedural steps and provides the physician with a simple, easy to use method of adjusting the location of a cuff without additional catheter assembly or trimming steps.
A further purpose of this invention is to provide an expander sheath that may be mounted around the shaft of a catheter and may be inserted between the inner wall of the cuff positioning device and the outer wall of the catheter shaft in order to allow the catheter to be exchanged with a new catheter, without removing the cuff.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as more detailed description is set forth below. Without limiting the scope of the invention, a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention.